In recent years, much work has been done [1]}-[2]} to determine the constraints leading to a quantum dynamics, and they appear in stages.There is no way around the fact that inference is a messy business, just as science, in general, is a messy business — we start with some constraints, modify them, and modify them some more until we begin to converge on a theory that is more appealing, in that it better explains, predicts, and controls the observed phenomenon. A preliminary constraint involves the introduction [3]}[4]} of an auxiliary variable \(\phi \) , the drift potential, which guides the probabilities; in a more familiar sense, \(\phi \)  is the mathematical manifestation of the `wave' part of De Broglie's famous `wave-particle' duality, or the pilot wave in Bohmian mechanics.Interestingly, the ED approach helps to clarify this duality: the particle aspect is real, the wave aspect is an epistemic property of the ensemble, not an ontological property of the particle. A secondary constraint emerges once we recognize that it is not just the evolution of \(\rho \) , but the coupled evolution of \(\rho \)  and \(\phi \)  that is important — namely, concerns arise as to how one updates the drift potential \(\phi \)  in response to the evolving probability \(\rho \) . Addressing this issue is one of the topics of this thesis.
